A conventional light indicator for a hard disk drive shows an operating status of the hard disk drive according to a logic level of an activity signal transmitted by a connector connected to the hard disk drive. However, for different types of hard disk drives, the activity signals used to represent an identical operating status (e.g., idling or accessing) may be different, so light indication is inconsistent among the different types of hard disk drives. For example, when operating in the accessing status, the activity signal of a hard disk drive supporting a Serial Advanced Technology Attachment (SATA) interface switches between logic-high and logic-low levels at a frequency of 4 Hertz (Hz), whereas the activity signal of a hard disk drive supporting Serial Attached SCSI (SAS) interface switches between logic-high and logic-low levels at a frequency of 1 Hz. In another example, when operating in the idling status, the activity signal of a solid-state drive supporting Peripheral Component Interconnect Express (PCIe) and is at a logic-high level, whereas the activity signal of a hard disk drive supporting SAS or SATA interface is at a logic-low level.